Only use the battery type recommended in the instructions. Although inexpensive, never use zinc carbon batteries. They are not designed to supply the current required for i-Torch lights.
Unfortunately all sizes and brands of alkaline batteries can leak corrosive liquid (potassium hydroxide solution) when mishandled or left for months stored in a flashlight. When this occurs the mechanism of the light will probably be damaged and the reflector surface may lose the shiny aluminum coating. Note: if the battery liquid touches your skin, wash it off immediately because it will cause a chemical burn.
Battery manufacturers recommend storing batteries at temperatures between 50°F (10°C) and 77°F (25°C), with relative humidity not exceeding 65 percent. Refrigeration of alkaline batteries is not necessary. Temperatures exceeding 130°F (54°C) should be avoided due to potential softening of the seal in the battery and subsequent leakage.
Also, batteries which are installed in an o-ring sealed light without observing the proper polarity, are not the same type, brand name and age or are completely discharged can vent hydrogen gas and possibly cause an explosion. To avoid these situations load batteries according to the diagram shown on the light or in the instructions. Do not mix batteries of different type, brand name or age. Discard all batteries as soon as they are drained or no longer produce light.
Rechargeable lithium ion battery packs should be charged before use for maximum burn time. They can self discharge at the rate of 5-10% per month. Charge the pack until the light turns green on the ac adapter.